必须保证在一个事务内处理：JDBC connection autocommit conn.setAutoCommit(false);

插入记录用empty_clob()函数带入空CLOB字段：Insert into table with CLOB column as empty_clob();

用select把空CLOB对象查出，并用for update子句来锁定这条记录：Select clob column with “for update” option like “select clob_field from clob_table where rowid=1 for update”;

将返回的CLOB字段对象由JDK的Clob转换成Oracle 库的CLOB对象：Turn the return from java.sql.Clob to Oracle.sql.CLOB:
    Clob clob = (Clob)rs.getClob("clob_field");
    oracle.sql.CLOB tmpclob = (oracle.sql.CLOB)clob;

用字符串填充该CLOB对象：
          BufferedWriter bw = new BufferedWriter(tmpclob.getCharacterOutputStream()); 
          bw.write(clobClValueArray.get(i).toString()); 
          bw.flush();
          bw.close();

用结构化语句对象PreparedStatement实现DML操作:
    PreparedStatement pstmt1 = conn.prepareStatement(“update clob_table set clob_field=? Where rowid=1”);
    pstmt1.setClob(1, tmpclob);
    pstmt1.execute();

把事务提交实现CLOB字段操作。Commit the update: conn.commit();

读取CLOB内容也很简单：
      PreparedStatement pstmt = conn.prepareStatement("select  clob_field from clob_table   where rowid=1");
       ResultSet rs = pstmt.executeQuery();
       Clob clob = (Clob)rs.getClob("clob_field");
       String str;  

        if(null != clob){
             str = clob.getSubString((long)1, clob.length());
    }

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